A fanciful depiction of the Battle of Shervan from a Thirteenth Century source.
Part Two - The Second Roman-Mongol War
The second Roman-Mongol War (1234 to 1235) was couched in religious terms, a war of faith waged against the darkness of paganism. In truth the inhabitants of Tus, the Roman territory conquered by Hulegu a decade before were Persian Muslims rather than Greek speaking Christians but better the Cross under the Roman than the harsh and alien gods of the barbarians. By framing the war in religious terms the Empress drew on the same passions stirred up by the Nubian invasion. This was not true cynicism - Agne was not a theologian but by all accounts her faith was genuine - but called back on the spirit of Heraclius, the Roman Emperor the Makedon's admired most.
While the soldiers of the standing army (the Tagmata retinues and the Varangian Guard, about 22,000 men in total) were stationed in the north eastern Persian city of Nishapur awaiting reinforcements from the theme levies, the Brotherhood of the Holy Sepulchre refused to wait. This holy order was a monastic fraternity that guarded the Holy Places, but though primarily composed of civilian monks and clergy they had a military arm too, not officially part of the Roman Army but eager to serve the Empress in the war against the pagans . On 1st March 1234 the Brotherhood easily defeated a small Mongol horde at Tus, which they settled down to besiege. Unfortunately they had reckoned without the sheer speed of the Mongols and on 14th April the Romans were annihilated at the Second Battle of Tus. The entire army lost; Roman sources claim the holy warriors died to a man though a generation later the Roman merchant John Dokeianos wrote of encountering green and blue eyed Greek speaking slaves in eastern most India, whom he was astonished to see knew the sign of the cross...
With the initial thrust blunted the Mongols invaded Roman territory in force. Östen though unable to save the Brotherhood had time to prepare a defensive strategy. This time the Mongols found the Roman Army ready for them and at Beyhaq on 4th August the decisive clash of the war took place. As before the Mongols had far more cavalry but this time the Romans fielded thousands of foot archers whose weapons outraged their enemies. When it came to close quarters the weight of the Roman infantry and heavy cavalry proved decisive. Not that the Romans had an easy victory; almost half of Östen's men died on the field, with the gallant archers suffering hideously as the fleeing Mongols broke through their lines. For the enemy on the other hand Beyhaq was nothing less than a nightmare. Three quarters of the Khagan's horde, the most ferocious warriors the world had seen since Atilla died on that day. The power of the Ilkhanate - and the terror it provoked - was broken on that day.
The Battle of Beyhaq, 4th August 1234 AD.
There were other battles, at Quaen (1st December) where the Romans avenged their defeat a decade before and at Shervan (14th January 1235) where Hulegu's horde were decimated and the defeated Mongol chieftain sued for peace. The Romans asked for the return of the territories ceded in 1224. The Empress swiftly restored the Bisophic of Tus, abolished by the Mongols during their rule.
It had been a great victory but could it have been greater? Hulegu has been criticised by historians for not carving out a new empire in Persia when the Romans had been helpless after the Battle of Gonbad-e Qabus. Had Agne made a similar misstep, fighting a ruinously expensive war in manpower and money to restore Roman rule over land to devastated to repay the cost? Perhaps, yet it is questionable the Romans had the strength to demand much more. Beyhaq had been a bloody victory indeed and Qaen and Shervan had carried heavy butchers bills. In January 1235 the Tagmata was less than half the size it had been a year earlier, the theme levies had been mauled and the Brotherhood of the Holy Sepulchre would take a generation to recover. Beneath the glory of victory, and explosion of support for the Empress the Romans were bone weary, having been through their third major war in twelve years. The sense of disillusion would see brief but startling revolts led by ex-soldiers in the Balkans (1236 & 1237) and Sinai (1237). Nor was the sense of exhaustion limited to violence. The Empress herself was robbed in July 1236, a brief but frightening experience that led some to question the wisdom of keeping the standing army in Persia, especially given the lapse of the Ilkhanate into civil war in the late part of the decade . Agne countered with the threat of the Indian states who had humbled the weakened Ghaznavids and might yet seek to drive the Christians from Sind.
The Second Roman-Mongol War (1234 to 1236 AD) & the post war revolts (1236 to 1237 AD).
With characteristic will power Agne swiftly recovered from her encounter with rogues and concentrated her energies on keeping the Roman Empire stable. Her eldest son and chosen heir Prince Gerasimos was wedded to the young and powerful Exarchessa Ioanna of Egypt, securing that all important province, but Ioanna’s sudden death in January 1236 left Gerasimos a nineteen year old widower. Agne appointed him the new Exarch of Egypt with his seat at Benghazi but despite his obvious ability the prince lapsed into depression, mourning his lost bride. Her second son, Prince Kallinikos married Queen Anastasia of Anatolia in November 1237. In her childhood Anastasia’s father had been killed in battle with the Mongols and some interpreted the Empress’ move as personal as much as political, a gesture of kindness to a family that had suffered much in the wars.
As wearying as her political life was Agne was still the same woman. 18th century historians uncovered letters addressed to Bishop Michael of Yedisu, tactfully described at the time as ‘Roman-Persian romantic poetry’ but more accurately described in modern times as ‘openly, unapologetically erotic’. Numerous theories have been advanced as to why the Empress seemed so enamoured of men of the cloth (and it must be said, they of her) but historians, perhaps thankfully, have yet to reach a consensus.
Empress Agne gave much thought to matters spiritual.
 The Brotherhood are an Orthodox Holy Order I've frequently used in Holy Wars and like the Varangian Guard are permanently hired (or were til now!)
 Yes, Agne was robbed while searching for a grail(!) It actually fits with her bodyguards in Persia and the revolts by 'disillusioned soldiers'.